Field of the Invention
The present invention relates to an image forming apparatus such as an electrophotographic copying machine and an electrophotographic printer (for example, a laser beam printer, an LED printer, and the like). In particular, the invention relates to controlling of determining a lifetime of a charging member of the image forming apparatus.
Description of the Related Art
In an image forming apparatus using an electrophotographic system, a charging roller of a contact charging system has been widely used as a charging member charging a photosensitive drum (an image bearing member).
In such an image forming apparatus, in order to continuously form an excellent image, it is necessary to perform replacement or refill of consumable supplies according to the setting of a lifetime of each apparatus or member. It is also necessary to replace the charging roller according to the lifetime. Therefore, a method of determining the lifetime has been proposed from the related art. For example, in Japanese Patent Laid-Open No. H09-211931, a configuration is described in which in the lifetime of the charging roller, it is determined that the lifetime is over when an applying time of a charged voltage applied to the charging roller and an integration value of the number of rotations of the charging roller reach a certain reference value.
An example of one factor affecting the lifetime of the charging roller is the occurrence of a charging failure by attaching toner onto a front surface of the charging roller. In a case where the charging failure occurs, vertical streak-like toner slipping occurs, and thus, the image failure is caused. Such attachment of the toner with respect to the charging roller considerably affects a variation in a physical property value of a cleaning blade which removes the toner on the photosensitive drum by scraping the toner, and a usage condition of the image forming apparatus.
For this reason, as with the configuration described in Japanese Patent Laid-Open No. H09-211931, in a case where the lifetime is determined by only information such as an applying time of a charging bias or the number of rotations of the charging roller, the lifetime determined according to the physical property value of the cleaning blade or the usage condition does not accord to an actual condition.